Submerged structures, such as ships, port facilities, buoys, pipe lines, bridges, excavators for seabed oil fields, water pipes in electric power plants or seaside plants, fishing nets, and rafts for aquaculture, suffer from adhesion of relatively large animals and plants, such as barnacles, hard-shelled mussels and lavers, and microorganisms, such as diatoms and bacteria, which leads to various damages, for example, corrosion of the structures, increase in sea water friction of ships, mass death of fishes due to jamming of the fishing net, sinking of structures due to weight gain, and reduction in working efficiency. In industrial water systems using natural water from rivers and lakes as, for example cooling water or in circulating cooling systems using moderately or highly purified city water, abnormal propagation of bacteria, diatoms, blue-green algae, spirogyra, etc. causes various troubles, such as deterioration of water qualities, reduction in cooling efficiency, obstruction of pipes, and reduction in flow rate.
In order to prevent these troubles caused by aquatic pests, it has been a practice to apply antifouling agents containing inorganic heavy metal compounds, such as copper suboxide, copper rhodanide, and mercury oxide, or organic metal compounds, such as tributyltin oxide, triphenyltin oxide, and tributyltin (meth)acrylate polymers.
However, these compounds which have been conventionally employed for the above-mentioned purpose are highly toxic, not only needing special care in handling but resulting in environmental pollution, including malformation of fishes due to accumulation in fish bodies. It has therefore been demanded to use an antifouling agent containing no heavy metals or organic metals.
Various compounds containing sulfur, such as thiuram compounds, benzothiazole compounds and thiocyanogen compounds, have been proposed as antifouling agents free from any heavy metal or organic metal, but their effects are still insufficient. A combined use of a dialkyl polysulfide compound with another pesticidal compound as an antifouling agent for fishing nets has been proposed as disclosed in Japanese Patent Laid-Open No. 38306/85. However, as the publication mentions, the dialkyl polysulfide compound per se has no biological activity.